International Research Journal of Plant Science (ISSN: 2141-5447) Vol. 3(10) pp. 222-229, December, 2012
Available online http://www.interesjournals.org/IRJPS
Copyright © 2012 International Research Journals
Full Length Research Paper
Correlation between some components of interior
plants and their efficiency to reduce Formaldehyde,
Nitrogen and Sulfur Oxides from indoor air
*Mohamed El-sadek1,2, Eid Koriesh2, Eijiro Fujii1, Eman Moghazy2 and Yehia Abd El-fatah2
1
Graduate School of Horticulture, Chiba University, Japan
Department of Horticulture, Faculty of Agriculture, Suez Canal University, Egypt
2
Abstract
Air pollution has become an extremely serious problem on human health especially in developing
countries. Sixteen ornamental plant species commonly used for interior plantscapes were screened
for their ability to remove three common indoor pollutants of formaldehyde, nitrogen oxides(NOx) and
sulfur oxides (SOx). Also, some components of the selected plants such as, ascorbic acid, chlorophyll,
pH, relative water content, leaf osmotic pressure as well as stomatal number, length and width on the
lower and upper leaf surfaces were assessed to determine the relationship between these
components and plant removal efficiency. Among the tested plants, Chlorophytum comosum
-1
Variegatum displayed superior removal efficiency for HCHO and SOx as 1830 µg day and 2120 µg
-1
-1
day and Spathiphyllum wallisii for NOx as 3200 µg day . Also, it was found that stomatal density can
be used as an indicator for the efficiency of indoor plants in the absorption of air pollutants;
especially for HCHO, SOx or NOx.
Keywords: Indoor pollutants; interior plants; HCHO; Sox; NOx, stomata; APTI
INTRODUCTION
Indoor air, being the lifeline for building occupants,
should be protected from the harmful effect of pollution
(World Health Organization, 2011). The air pollutants or
substances selected for this study, formaldehyde
(HCHO), nitrogen oxides (NOx), and sulfur oxides (SOx)
are common indoor air pollutants. HCHO is a pungent
gas that can irritate a person’s eyes, nose, throat, and
lungs. The risks posed by air pollutants are to lung
disease, including respiratory tract infections, asthma,
and lung cancer (Public Health Agency of Canada,
2005). The risk of formaldehyde poses to a person’s
health depends on the concentration of HCHO in the air,
the length of exposed, and the person’s individual
sensitivity to HCHO. The American Air Resources Board
has identified formaldehyde as a toxic air contaminant,
based on its potential to contribute to cancer risk
(Granholm, 2004). Reducing indoor formaldehyde from
*Corresponding author Email:pathologist2011@yahoo.com
indoor air will reduce the risks to human (World Health
Organization, 2011).
Nitrogen dioxide (NO2) acts mainly as an irritant
affecting the mucosa of the eyes, nose, throat, and
respiratory tract. Extremely high-dose exposure (as in a
building fire) to NOx may result in pulmonary edema and
diffuse lung injury. Continued exposure to high
NOx levels can contribute to the development of acute or
chronic bronchitis. Low level of NOx exposure may
cause increased bronchial reactivity in some asthmatics,
decreased lung function in patients with chronic
obstructive pulmonary disease and increased risk of
respiratory infections, especially in young children. In
homes with gas stoves, kerosene heaters, or un-vented
gas space heaters, indoor levels often exceed outdoor
levels (Kornartit et al., 2010). Generally, the risk of
pollutants poses to a person’s health depends on the
concentration, the length of exposed, and the person’s
individual sensitivity (World Health Organization, 2002).
Health effects caused by exposure to high levels
of
SOx include
breathing
problems,
respiratory
illness, changes in the lung's defenses, and worsening
ELSadek et al. 223
respiratory and cardiovascular disease. People with
asthma or chronic lung or heart disease are the most
sensitive to SOx (Chapd, 2010). Indoor plants are a
healthy option to reduce formaldehyde by helping
cleanse the breathing space, besides; reducing indoor
NOx and SOx are a significant goal for interior
landscapers, through using the selection of highly
efficient plants to reduce the risk to human health (Xu et
al., 2011).
The most important step to reduce exposure to the
selected pollutants HCHO, NOx and SOx, is to increase
indoor air quality through reducing levels of these
pollutants, while at the same time reducing indoor CO2. The
most promising method to achieve this aim is by using
suitable indoor plant species (Burchett et al., 2007).
The responses of plants to pollutants may provide a
simple link concerning phytoremediation of air pollutants
to admit air pollution abatement. To develop the use of
plants as phytoremediators it requires an appropriate
selection of some plant constituents or characters to be
investigated. This study is based on the approach of
Singh et al., 1991, which was directed to outdoor air
pollution responses. The researchers developed a
method of using plants to indicate severity of urban air
pollution by deriving an Air Pollution Tolerance Index
(APTI). The APTI for each species tested involved
measurements that were carried out on levels of
ascorbic acid, chlorophyll a and b, relative water content,
and leaf extract pH. These characters were studied in
this work as well as osmotic pressure of leaf sap,
stomatal density, stomata length and stomata width in
both sides of plant leaves of the selected indoor foliage
plants.
It is evident that a better understanding of the
phytoremediation potential of a diverse range of indoor
plants is also needed. In this study, a cross-section of
indoor plants, sixteen species were tested for these
properties for the first time, these being among the most
commonly used international species and for interior
landscapes. The species were screened for their ability
to reduce HCHO, NOx and SOx and were also analyzed
to find the relationships between some of plant
components and plant efficiency to air pollution
abatement.
Material and Methods
Plants material and growth conditions
Dieffenbachia picta, Epipremnum aureum, Codiaeum
variegatum, Cordyline terminalis, Spathiphyllum wallisii,
Euonymus
japonicus,
Syngonium
podophyllum,
Aglaonema pictum, Ruscus hypoglossum, Chlorophytum
comosum, Dracaena marginata, Yucca elephantipes,
Sansevieria
trifasciata,
Schefflera
actinophylla,
Chlorophytum comosum Variegatum and Ficus
benjamina (Table 1) were obtained from commercial
source. Similar individuals of each species were chosen
as replicates. Plants were individually planted in 18-cmdiameter pots containing a standard potting medium.
The plants were acclimated for several weeks to
approximately the same environmental conditions of
lighting, temperature, relative humidity, etc., in order to
minimize stress.
Gases exposure and monitoring
Individual plants were placed in a growth chamber. It is a
250 L gas-tight test chambers covered with 100 micron
plastic. The growth chamber exposed to 50 fold normal
3
3
pollutant concentrations as 3000 µg/m , 5000 µg/m and
3
4000 µg/m of HCHO, NOx and SOx, respectively. Plants
were individually placed in the chamber, and then
injected with either HCHO or NOx or SOx. Plants were
left in the chambers for 24 hours. Three replications of
each species were tested. An empty chamber was
injected with each pollutant and left without plants as a
control. The gas concentration within the chamber was
determined after 24 h and compared with the control.
A randomized complete design was used with three
experiments. Each experiment consisted of the
individual pollutant and the tested species.
APTI values were determined by calculating the
ascorbic acid, chlorophyll, pH and relative water
contents in leaf samples. Ascorbic acid was estimated
by 2, 6 - dichlorophenol indophenol dye following the
method of (Madhoolika, 1985). Chlorophyll was
calculated by spectrophotometer and pH was
determined by digital pH meter. Relative water content of
leaf material was estimated by taking the initial weight
and dry weight of leaf material. The air pollution
tolerance indexes were determined following the method
of (Singh and Rao, 1983), the formula being as follows:
APTI = [A (T+P) + R]/10
Where A = ascorbic acid content (mg/g), T = total
chlorophyll (mg/g), P = pH of leaf extract, and R =
relative water content of leaf (%).
The stomata numbers were measured from an
imprint of the lower and upper leaf surface peeling it off
(Hamill et al., 1992). The stomata density was measured
2
at 100x magnification per cm .
Total soluble solids (TSS) were determined by
rafractometer (stalks) according to Association of Official
Analytical Chemists, (1996). Leaf osmotic pressure was
calculated by multiplying total soluble solids in leaf sap
by the factor 0.36 (William, 1980).
RESULTS AND DISCUSSION
The results showed that the removal efficiency of each
gas pollutant by the studied plants varied according
to the pollutant and the species. The ability of every
indoor plant to remove HCHO, NOx and SOx from sealed
224 Int. Res. J. Plant Sci.
Table 1. Family, Latin binomial, common name, and Leaf area of test plants exposed to three indoor air pollutants (Formaldehyde, Nitrogen
and sulfur oxides) over 24 hours
No.
Family
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Araceae
Araceae
Euphorbiaceae
Agavaceae
Araceae
Celastraceae
Araceae
Araceae
Asparagaceae
Asparagaceae
Agavaceae
Agavaceae
Agavaceae
Araliaceae
Asparagaceae
Moraceae
2
Latin binomial
Common name
Leaf area (m /plant)
Dieffenbachia picta Jacq
Epipremnum aureum
Codiaeum variegatum L.
Cordyline terminalis
Spathiphyllum wallisii Regal
Euonymus japonicus
Syngonium podophyllum Schott
Aglaonema pictum (Roxb.) Kunth
Ruscus hypoglossum
Chlorophytum comosum Thunb
Dracaena marginata
Yucca elephantipes
Sansevieria trifasciata Prain
Schefflera actinophylla (Hayata) Merr
Chlorophytum comosum Variegatum Thunb
Ficus benjamina L.
Dumb cane
Pothos
Croton
Hawaiian Ti
Peace lily
Japanese Spindle
Arrowhead vine
Chinese evergreen
Mouse Thorn
Spider plant
Red-edge Dracaena
spineless yucca
Snake plant
Dwarf Umbrella Tree
spider plant
Weeping fig
0.06
0.06
0.02
0.05
0.11
0.04
0.10
0.28
0.23
0.13
0.15
0.18
0.39
0.13
0.29
0.31
Figure 1. Removal of HCHO, NOx and SOx from the air inside sealed
experimental chambers using test plants
experimental chambers are demonstrated in Figure. 1.
Chlorophytum comosum varigatum, D. marginata and A.
pictum plants were more efficient in reducing HCHO.
Meanwhile, S. wallisii, F. benjamina and C. comosum
absorbed more NOx than the other tested plants and C.
comosum varigatum, C. varigatum, S. podophyllum
removed more SOx than the other species.
APTI values were calculated for the tested plants in
an effort to find a relationship between the removal
efficiency of studied plants and these biochemical
parameters that could indicate the tolerance or
sensitivity to the contaminants (Table 2 and Figure. 2). It
is clearly shown that there was no specific trend in this
concern.
Air pollutants may get absorbed, accumulated,
metabolized or integrated in the plant metabolism.
Besides, it may be toxic or injury plants in various
ways depending on plant species and pollutant type and
ELSadek et al. 225
Table 2. Stomata density, stomata length, stomata width, total soluble solids, osmotic pressure and air pollution tolerance index of
tested plants exposed to three representative indoor air pollutants(Formaldehyde, Nitrogen and sulfur oxides) over 24 hours
Plant
D. picta
E. aureum
C. variegatum
C. terminalis
S. wallisii
E. japonicus
S. podophyllum
A. pictum
R. hypoglossum
C. comosum
D. marginata
Y. elephantipes
S. trifasciata
S. actinophylla
C.comosum varigatum
F. benjamina
Stomata density/ cm 2
3700
3900
16400
11000
7900
24500
9500
4800
6000
10800
10200
9000
4700
14900
12600
21800
Stomata length µm
64.13
30.32
37.13
25.84
43.28
27.14
27.29
55.43
24.59
39.36
37.41
35.71
38.57
28.71
47.44
35
Stomata width µm
31
13.55
25.7
15.81
24.65
18.57
12.12
33.24
16.72
14
34.29
31.43
25.71
14.62
26
18.48
TSS
3
3
6
7
4
5.5
3.2
2
5
1.9
2.9
10.6
4.1
5.9
1.8
6
OP
1.08
1.08
2.16
2.52
1.44
1.8
1.15
0.72
1.8
0.68
1.04
3.81
1.47
2.12
0.64
2.16
APTI
13.95
11.92
13.04
12.29
13.13
13.47
11.48
12.37
14.53
11.21
15.92
39.21
13.87
13.79
11.06
14.56
Figure 2. Relationships between plant efficiency to remove HCHO, NOx and SOx and APTI of test
plants
concentration. The sensitive species may be used as air
pollution indicator. On the other hand the presented data
of the APTI components and plant morphology indicated
that there are relationships between APTI and plant
tolerance or sensitivity to the pollutants. In the present
study, out of Sixteen species examined, Y. elephantipes,
D. marginata, F. benjamina and R. hypoglossum showed
their tolerance to the tested air pollutants, since
exposure to the pollutants did not result in any apparent
damage to these four species. On the same time, the
remaining plants species showed varying degrees of
sensitive responses when exposed to the studied
pollutants. The levels of injuries depend on the species.
The types of injury resulting from pollutant exposure are
exemplified in Figures. 7 and 8.
SOx injury appears as large brown area or yellow
areas changes to brown areas in both sides of the leaf
shown in Figure. 7. While symptoms of NOx injury have
included chlorosis, there are different foliar symptoms as
shown in Figure. 8.
The results shown in Table 2 also, indicated that
there were no relationships evident between the studied
226 Int. Res. J. Plant Sci.
Figure 3. Relationships between plant efficiency to remove HCHO, NOx and SOx and stomata number of
test plants
Figure 4. Relationships between plant efficiency to remove HCHO, NOx and SOx
plants
and stomata length (µm) of test
ELSadek et al. 227
Figure 5. Relationships between plant efficiency to remove HCHO, NOx and SOx and stomata width(µm) of test plants
Figure 6. Various types of stomata density, length and width of D. picta
(A), C.comosum variegatum (B) and E. japonicus (C) bar 50 µm
Figure 7. SOx injury on leaves of S. podophyllum (A), S. wallisii (B) and D.
picta (C).
228 Int. Res. J. Plant Sci.
Figure 8. NOx injury on leaves of C. comosum varigatum (A), C. terminalis
(B) and E. aureum (C)
pollutants HCHO, NOx and SOx and the studied plant
characters or components as TSS and, OP. The data
from the same Table 2 indicated that there was a parallel
link between pollutants abatement from the growth
chamber and stomata density on both sides of leaves.
Figures. 3 and 6 showed a close parallels between
pollutant abatement and stomata number per plant (r =
0.48,0.32,0.36 for HCHO, NO2 and SO2 respectively).
The results are in harmony with those of Martin et al.,
(2002) which indicated that there stomatal responses
were involved in responses to the pollutant SOx. They
are also in line with the finding of Papinchak et al.,
(2009), they revealed that the plant’s ability to reduce
pollutants from surrounding environment appears to be
depending on the uptake of pollutants through the
stomata. Also, Sukumaran, (2012) concluded that the
differences between plants in their stomatal number
were found to be significant in pollutants uptake
efficiency. The results also indicated that there were a
relationship between HCHO, NOx and SOx abatement
and either stomata length and width as shown in figures
4 and 5.
In summary, the results of this study confirm that the
competencies of the plants under investigation were
clearly linked to some characteristics or components of
the plant, in particular the stomatal density, length and
width of their foliage. Therefore, stomata number per
plant can be used for primary rudimentary knowledge
about the efficiency of specific plant for indoor air
pollution abatement. Also, this work is in accordance
with the results of the previous work by Boubel, et al.,
(2008) where the indoor plants showed efficiency in
decreasing the concentration of specific indoor pollutants
The investigation has also provided information on the
efficiency of the plants to remove these pollutants, and
helps lay the foundation for developing enhanced
efficiency among houseplants for air pollution removal.
More researches are required with other species, to
investigate the linkage between this leaf characteristic
and possible removal of other air pollutants.
ACKNOWLEDGEMENT
We gratefully acknowledge the financial support from the
Egyptian Ministry of higher education.
REFERENCES
Association of Official Analytical Chemists (1996). Official Methods of
Analysis, Association of Official Analytical Chemists, Washington
DC.
Boubel RW, Fox DL, Turner DB, Stern AC (2008). Fundamentals of Air
Pollution. 4th edition. Academic Press. USA.
Burchett M, Tarran J, Torpy F (2007). Potted-plants improve indoor
environmental quality. University of technology publication, Sydney.
http://plantsolutions.com/documents/PottedPlants Improve Indoor
Environmental Quality.pdf .
Chapd HQ (2010). Sulphur dioxide, Incident management. Health
protection
agency
UK.
http://
www.hpa.org.uk/
Topics/ChemicalsAndPoisons/Compendium
Of
Chemical
Hazards/Sulphur Dioxide/.
Granholm JM (2004). What is an Air Contaminant/Pollutant? Fact
sheet. The Michigan Department of Environmental Quality. Michigan
University. http://www.michigan.gov/documents/deq/deq-ead-caapairconfs_281871_7.pdf.
Hamill S, Smith MK, Dodd WA (1992). In vitro induction of banana
autotetraploid by colchicine treatment of micropropagation diploids.
Australian journal Botanical, 40: 887–896.
Kornartit C, Sokhi R, Burton M, Ravindra K (2010). Activity pattern and
personal exposure to nitrogen dioxide in indoor and outdoor
microenvironments. Environ. Intern., 36: 36–45.
Madhoolika A (1985). Plant factors as indicator of SO2 and O3. In
Biological monitoring of state the environment (bioindicator).Indian
National Science, New Delhi. pp 225–231.
Martin M, Evans NH, Mongomery LT, North KA (2002). Stomatal
responses to gaseous pollutants. New Phytologist, 153. pp. 441–
448.
Papinchak HL, Holcomb EJ, Orendovici T, Decoteau DR (2009).
Effectiveness of Houseplants in Reducing the Indoor Air Pollutant
Ozone. HortTechnology, 19: 286–290.
Public Health Agency of Canada (2005). Proposed residential indoor
air quality guideline for formaldehyde. 31 p.
Singh SK, Rao DN (1983). Evaluation of the plants for their tolerance
to air pollution Proc. Symp on Air Pollution control held at IIT, Delhi
218–224.
Sukumaran D (2012). Effect of Particulate Pollution on various Tissue
Systems of Tropical Plants. ECO Services International. Green
Pages. http://www.eco-web.com/edi/120208.html.
ELSadek et al. 229
William W (1980). Measurement of Tissue Osmotic Pressure. Plant
Physiol. 65(4): 614–617.
World Health Organization (2002). The World Health Report 2002—
Reducing Risks, Promoting Healthy Life. Available at:
http://www.who.int/whr/2002/en.
World Health Organization (2011). Air quality and health. Fact sheet
N°313..
http://www.who.int/mediacentre/factsheets/fs313/en/index.html.
Xu Z, Wang LL, Hou HH (2011). Formaldehyde removal by potted
plant-soil systems. J Hazard Mater 192(1):314 – 318.